Funding for this research was provided by:
National Natural Science Foundation of China (81601242)
Natural Science Foundation of Jiangxi Province (20161BAB215199)
Received: 28 November 2017
Accepted: 30 January 2018
First Online: 6 February 2018
Ethics approval and consent to participate
: Not applicable (review article).
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.